Conventional wireless devices are designed to work or operate in a specified frequency range or band with limited transmit power levels. The major types of frequency bands regulated by the Federal Communications Commission (FCC) include licensed bands, semilicensed bands, unlicensed bands and overlapped bands. The FCC has specific transmit power limits for each of the described bands to provide public safety and to reduce potential co band and adjacent band interference levels.
Example licensed frequency bands include cellular telephony or Personal Communication Service (PCS) bands, as well as Advanced Wireless Services (AWS) bands and Global System for Mobile Communications (GSM) bands. Cellular communications in the U.S. typically operate in the frequency ranges of 824-849 MHz, and 869-894 MHz. Further bands include 700 MHz bands, such as Band 12. Broadband PCS communications in the U.S. typically operate in the frequency ranges of 1850-4910 MHz and 1930-1990 MHz, while narrowband PCS typically operates in the frequency ranges of 901-902 MHz, 930-931 MHz, and 940-941 MHz. The 4940-4990 MHz band (referred to as the 4.9 GHz licensed band) is available but is designated by the FCC for support of public safety. Other licensed bands, such as those supporting Third Generation (3G) wireless communications, include frequency bands such as 1710-1755 MHz, 2110-2155 MHz, 2305-2320 MHz, 2345-2360 MHz (Wireless Communication Services, WCS band), and 2500-2690 MHz (Multichannel Multipoint Distribution Services, MMDS band).
Licensees to a licensed band usually have an exclusive right to provide services with the band in a specified geographic area, for a defined term and within specified times. The license is exclusive in the sense that no other service providers are typically allowed to provide services in the same band, in the same area and at the same time. Other licensed bands include, but are not limited to, a licensed band identified as allocated for WiMax (WiMAX is defined as Worldwide Interoperability for Microwave Access).
A semilicensed band in the 3.65 GHz to 3.7 GHz range is a nationwide band available to all licensees under nonexclusive terms. Licensees to the semilicensed band are required to coordinate among themselves to reduce mutual interference levels and to share the band equally when coexisting within the same region. The semilicensed band is free to all licensees and no limit is set on the number of licensees.
Unlicensed frequency bands such as Industrial Scientific and Medical (ISM) frequency bands and Unlicensed National Information Infrastructure (UNII) frequency bands are well known and can be shared by any number of devices. These unlicensed bands typically include frequencies such as 900 MHz, 2.4 GHz, 5.0 GHz and 5.8 GHz, which are commonly used for cordless telephones, wireless local area networks (WLANs) and Bluetooth devices.
Overlapped bands are frequency bands within the range from 3.1 GHz to 10.6 GHz. An example overlapped band is allocated for the use of so called ultra-wideband (UWB) devices. The UWB band is an unlicensed frequency band that overlaps with many licensed bands within its frequency range.
Radio communication links each utilize one or more component carriers in a single frequency band. Thus, a radio communication link may involve resource blocks or channels from one frequency band, such as a licensed, unlicensed, semi-licensed, or overlapped frequency band. This often results in certain frequency bands being heavily utilized and other frequency bands being underutilized.